a) Field of the Invention
The invention is directed to a closure for connecting two thin walls, such as sheet metal cabinet doors to sheet metal cabinet frames, which comprises a bearing piece, mounted in or on an opening in the first thin wall and a shaft, retained in the bearing piece wherein it may be rotated and axially displaced. A pivoting lever is mounted on the one, outer end of the shaft and, on the other, inner end of the shaft, a retaining piece is arranged, wherein the pivoting lever can be pivoted from a first, open position where the shaft is in a first axially loaded position into a second, closed position where the shaft has been displaced axially outwards against the force of a spring.
b) Description of the Related Art
Such a closure is already known, cf. for example DE 44 23 406 A1.
The object referred to as an xe2x80x9cAusbauchverschlussxe2x80x9d (convex or bellying closure) in this document makes it possible to secure two plate-like parts to each other or one plate-like part to a corresponding frame. The closure described in this document has the advantage of great simplicity, since it needs relatively few parts and can be fitted relatively simply.
Nonetheless, it also has disadvantages that forbid its use for certain applications. Especially when the closure is supposed to work at low temperatures, as they are for example present in refrigerating chambers, resulting in the disadvantage that the body of expanded material, which for example consists of elastic rubber or plastic, loses its elasticity because of the low temperature and could even break if this leads to brittleness.
There is the further disadvantage that the closure is immediately open completely when the operating lever is swung open accidentally, so that there is a risk that the two thin walls move apart unintentionally, which can for example lead to a refrigerating chamber being opened unintentionally.
It is the primary object of the invention to improve a closure of the type described in the opening section in such a way that the described disadvantages no longer occur.
In accordance with the invention, this object is met by making the retaining piece comprise a cupular guide piece and a sleeve piece, which may be inserted in and rotated in the cupular guide piece against the force of a spring. A catch projects from said sleeve piece in the direction of the wall plane which, in the engaged position, extends beyond the outer surface of the guide piece as far as the rear surface of the second thin wall and rests thereon.
First of all, these features avoid the use of a body of expanded material, which at low temperatures might not be sufficiently flexible anymore and therefore might lose its function or break during attempts of use because of brittleness, and the ability of the two connected walls to move completely away from each other when the pivoting operating lever is swung away is also removed. When the operating lever of the closure according to the invention is merely swung open, the closure is opened and the connection of the two walls is loosened, but the two walls can not be separated from each other; for this, the lever handle must additionally be rotated, for example by 180 degrees.
Whereas in prior art the spring forces and locking forces must be generated by the body of expanded material, resulting in the described disadvantages at low temperatures, the novel closure according to a further development of the invention has the spring force being generated by a spiral spring arranged between the bottom of the cup of the guide piece on one side and on the face of the sleeve facing the bottom of the cup on the other side. This spring is largely independent of temperature influences.
So that as in prior art the construction and installation are as simple as possible, it is advantageous if the opening in the second thin wall is circular with two widening sections (for example corresponding to the cross-section of a two-way key) and if the catch part can be slid through the opening like a bayonet in one rotary position of the rotating sleeve part but not in another position, for example one rotated by 90 degrees.
If one wants to avoid the expense of producing a two-way key opening in the door-frame, according to another embodiment form the shaft could be guided through the bottom of the cup in a location that is eccentric relative to the circumference of the cup. This makes it possible for the catch to engage behind the wall in a first rotary position, while in a second rotary position the catch can be passed through the opening.
According to yet another embodiment form of the invention, the lever can form a cam surface that rests on the outer face of the bearing piece. For prior art, the corresponding support is formed by the thin wall itself, which simplifies construction, but on the other hand can lead to unsightly paint damage that can lead to the formation of rust in visible places.
The outer face of the bearing piece can form a groove shaped like part of a circle or a conical depression into which lugs, carried or formed by the lever, extend during its closing pivoting movement. This makes it possible to only allow the closing pivoting movement of the lever in such a position that is optimally suitable, whereas in other positions the pivoting of the lever is not possible because of the lack of a grooved area. This has the advantage that a closing pivoting movement is only possible in a position where the catch engages sufficiently safely behind the second wall.
According to yet another embodiment of the invention, the sleeve carrying the catch is held on the shaft by a self-locking nut. This has the advantage that the closing force can be set as required by way of screwing the nut further onto or off the bolt.
According to yet another embodiment of the invention, it can also be advantageous to place a spring washer between the self-locking nut and the catch sleeve for the purpose of compensating for small differences in tolerance.
According to yet another embodiment of the invention, it is advantageous for the outside of the bottom of the cupular part to have a projection which is matched by a correspondingly shaped opening in the thin wall in such a way that the cupular part is secured against rotation relative to the thin wall; this is to ensure that the cupular part does not twist relative to the thin wall and in so doing makes a closing position indefinable.
The projection could in particular have a non-round cross-section which fits into an opening in the thin wall which also has a non-round cross-section and thus is secured against twisting.
Alternatively, the thin wall could also have additional openings into which lugs coming from the bearing protrude, but this does require additional openings in the thin wall, which sometimes are impractical.
Instead of the lug or the several lugs, threaded boreholes can be provided into which (countersunk head-) screws can be screwed which come from the bearing or which can be passed through corresponding boreholes in the bearing.
This design is particularly tamper-proof.
A simple construction is made possible when according to another further development of the invention the opening in the first wall is an elongated hole into which the cross-section of the shaft fits essentially without any play. By this, securing it against rotation is achieved without additional boreholes, and the opportunity for adapting to different conditions also exists.
This is in particular the case if the opening in the first wall is an elongated hole into which the cross-section fits with play.